CO2 storage capacity as sediment-hosted gas hydrates in the area of the celtic sea and the bay of Biscay : first modeling results and experimental research roadmap
Résumé
The storage of CO2 under supercritical conditions in deep saline aquifers is presently the most studied storage option. However, the trapping of CO2 in deep-sea sediments at low temperature is another option: either as a liquid or as gas hydrates, or both. The storage capacity as gas hydrates depends strongly on the local geothermal gradient as well as the quality of the CO2 stream after the capture process. In order to evaluate the effect of these parameters, a new numerical tool using well-proven accurate modules (GERG-2008, CSMGem and GMT) has been designed and applied in the Celtic Sea and the Bay of Biscay area. The best estimate of the storage capacity in the French Exclusive Economic Zone (EEZ) is found to be higher than in the deep saline aquifers of the Paris Basin. Moreover, the storage capacity would be twice the predicted one when considering the zone beyond 200 miles from the shores. These first results allowed us to identify key properties which need to be measured in order to improve the modeling approach. Accordingly, an experimental research roadmap is proposed in order to better assess the operability of a deep offshore storage. The implications of this research are potentially important for the long-term CO2 storage deployment strategy both in France and in Western Europe.